<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .box1 {
        width: 100px;
        height: 100px;
        background-color: red;
    }

    .inner {
        width: 50%;
        height: 50%;
        background-color: green;
    }

    /* 谷歌浏览器默认字体16px */

    .box2 {
        width: 1em;
        height: 1em;
        background-color: orange;
    }

    /* 1em即父元素字体的大小 */
    .wrap {
        font-size: 100px;
    }

    html {
        font-size: 100px;
    }

    /* 1rem即跟标签的字体大小  html  */
    .box3 {
        width: 1rem;
        height: 1rem;
        background-color: yellow;
    }

    /* 1vh指页面高度的1% */
    .box4 {
        width: 50vh;
        height: 50vh;
        background-color: green;
    }

    /* 1vw指页面宽度的1% */
    .box5 {
        width: 1vw;
        height: 1vw;
        background-color: purple;
    }

    /* vmin vh和vw中谁小参考谁 */
    .box6 {
        width: 10vmin;
        height: 10vmin;
        background-color: pink;
    }

    /* vmax vh和vw中谁大参考谁 */
    .box7 {
        width: 10vmax;
        height: 10vmax;
        background-color: black;
    }
</style>

<body>
    <!--  <div class="box1">
        <div class="inner"></div>
    </div>
    <div class="wrap">
        <div class="box2"></div>
    </div>
    <div class="box3"></div>
    <div class="box4"></div>
    <div class="box5"></div> -->
    <div class="box6"></div>
    <div class="box7"></div>
</body>

</html>